Dynamo-electric machine



Sept. 22, 1925.

E. P. LEE

DYNAMO ELECTRIC MACHINE 7 Filed May 10. 1922 1 B W H UNITED STATES PATENT OFFICE EARLE r. LEE, or nocnnsraa, some ASSIGNOR NQRTH EAST ELECTRIC COM- PANY, OF ROCHES NEW' YORK, A. CORPORATION OF NEW YORK.

DYNAMIC-ELECTRIC MACHINE.

Application filed May 10, 1922. Serial No. 559,777.

To all echo-m it may concern:

Be it known that I, EARLE P. LEE, a citi' zen of the United States, residing at Rochester, in the county of Monroe and Estate of New York, have invented certain new and useful Improvements in Dynamo- Electric Machines; and I do hereby declare the following to be a full, clear, and exact descriptionof the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to the field-windings of dynamo-electric machines. It is particularly applicable to the field-winding of a machine of the enclosed type, though it may also be useful in other applications.

The ,object of the invention is primarily to produce a winding of the greatest possible compactness, and incidentally to provide a simple and rugged structure which may be inexpensively manufactured.

To these ends it is proposed to use a strip of sheet-metal as the material of the winding, this sheet-metal being punched or cut in a serpentine shape, and being then coiled lengthwise in cylindrical form, with insulation between adjacent layers. In order to avoid unsyimnetrical distribution of flux in the pole-pieces of the machine, the invention, in its most complete embodiment, comprises the use of two of such strips of sheetmetal, so arranged as completely to surround or embrace each pole-piece.

Other objects and advantageous :tcatures ot the invention will be set forth. hereinafter, in connection with the description of the illustrated embodiment of the invention.

In the drawings, Fig. 1 is a developement ot the field-magnet of a four-pole dynamoelectric machine embodying the present invention, as seen from the inside and with the pole-pieces in section. Fig. 2 is a partial end-view on a larger scale, of the fieldmagnet of the same machine. Fig. 3 is similar to Fig. 1 except that it shows a field-winding with two overlapping parts. Fig. 4 is a detail-view showing a mode of attachment of one of the terminals of the winding.

In Fig. '1 the invention is illustrated as embodied in a four-pole motor of the type in which the field-magnet comprises a tubiilar body or ring 5 with separable polepieces 6. These pole-pieces are secured to the fieldring by screws 7. The winding, characteristic of the present invention, is in the form of a continuous strip of sheetmetal recessed or notched alternately from its opposite longitudinal edges so as to provide parallel transverse members 8 connected by longitudinal members 9. The recesses give the winding serpentine form, such that it may pass alternately around opposite ends of adjacent pole-pieces, and the winding is coiled lengthwise in a generallycylindrical form, with an interposed strip of insulating-material 10, so as to produce several. layers in which the recesses are in radial coincidence, so that they may embrace cach pole-piece on three sides. The ends of the strip are extended laterally to form terminals 12 and 13, by which the winding may be connected, in any conven ient manner, with the armature and terminals (not shown) of the machine.

It will be understood that the winding is first formed, then introduced into the field-ring, and then secured in place by the attachment of the p0lepieces to the ring. The edges of the winding are insulated from the pole-pieces by suitable material 11.

The single winding of Fig. 1 causes more or less irregular distribution of dun in the field, and where this is undesirable it may be avoided by dividing the field-winding into two similar strips and winding them so that their terminals are spaced apart by one pole, as shown in Fig. 3. In this case equal numbers of turns pass around both ends of each pole-piece.

The two strips may be connected either in series or in parallel, and they may be wound either together or separately. In Fig. 3 they are shown as wound together, so as to form a double spiral. When wound separately, each strip will form a single spiral like that of Figs. 1 and 2, and one spiral will be placed inside the other.

For economy in manufacture the terminals 12 and 13 may be made as separate pieces of sheet-metal and brazed to the body of the winding, as shown in Fig. 4 where the terminal 13 is secured by a brazed joint 14 of well-known form.

I am aware that wide, thin strips of metalv have been used for field-windings in dynamo-electric machines, but in such cases the strips have always been of uniform width and of originally straight form, and

have been coiled around each pole separately. here such coils are of helical form it is necessary to bend the strip edgewise, which is a difficult and expensive operation. \Vhere the coils are of spiral form there is no convenient way of bringing out the inner terminals. By the present construction both of these difliculties are avoided as the terminals are all located at the most convenient points, and no bending is neces sary except that involved in the very simpl operation of coiling the strips to the cylind-rical form of the field-ring.

Another important advantage of the present winding is the fact that it may be made of unusually low resistance for the space available. This is due partly to the relatively small space occupied by insulation, but chiefly to the fact that all of the space between the pole-pieces may be utilized. As shown in the drawings, the parts 8 may be of the full width of the spaces between the pole-pieces, while the parts 9 are not necessarily of the same width, but may be as much narrower as is necessary to keep the length of the machine within bounds. This feature is especially advantageous in motors in which it is desired to secure a very large torque during short periods of overload, as, for example, in the motors used to start or crank internal-combustion engines.

The invention is not limited to the en1- bodiment thereof hereinbefore described and illustrated in the accompanying drawings, but it may be embodied in various other forms within the scope of the following claims.

The invention claimed is:

1. In a dynamo-electric machine, the com bination, with a tubular field-ring and polepieces projecting inwardly therefrom, of a field-winding 1 comprising a continuous strip of sheet-metal recessed alternately at opposite edges to give it a serpentinue form and coiled lengthwise into generally cylindrical form, with the recesses in radial coincidence in the several layers, said winding fitting closely within and being coaxial with said field-ring and the pole-pieces occupying the spaces provided by said lateral recesses.

2. A dynamo-electric machine, as defined in claim 1, in which two similar strips are used in the fieldwinding, with their corresponding recesses displaced by one pole so that each pole-piece is embraced 011 all sides.

EARLE P. LEE. 

